1. Field of the Invention
This invention relates to improvements in or relating to a spring producing technique which is constituted such that a wire stock is fed intermittently by a pair of wire stock feeding rollers consisting of a drive roller and a follower roller and is pressed against and bent by a deflecting face of an opposing bending die whereafter it is wrapped into coils around a metal core while a predetermined pitch is being applied to the wire stock by means of a pitch tool and is finally cut by a cutter, and more particularly to a spring producing apparatus which is designed such that the developing length, the configuration of a pitch and so on can be changed suitably in producing a spring.
Further, the second invention relates to a spring producing apparatus wherein, in producing a coil spring or in experimentally producing a coil spring, feeding of a wire stock or the profile of a pitch can be suitably changed by a simple mechanism and the spring producing apparatus can be utilized also as an experimental coil spring producing apparatus.
2. Prior Art
Generally, pneumatically controlled automatic spring producing machines and automatic spring coiling machines are well known. However, since such machines are very expensive, they lead to a high cost unless they are applied for mass-production. Thus, it is a drawback of such machines that they are not suited for production of a large number of products in a small quantity.
Particularly, it is quite impossible to utilize a large-size spring machine as an experimentally producing machine.
Known as a spring machine which can be replaced by such a large-size spring machine is a spring producing apparatus 30 shown in FIG. 8.
The spring producing apparatus 30 of the type mentioned includes a crank device 32, a connecting rod 33 and a sector gear 35 connected in this order to a main shaft 31 which is being continuously rotated in one direction by a motor not shown. Accordingly, the sector gear 35 is rocked reciprocally around a shaft 36, and the rocking motion of the sector gear 35 is taken out as rotation of a drive roller 39 in one direction via a one-way clutch not shown. A follower roller 40 is held in contact with and rotated following the drive roller 39, and a wire stock 42 is held between and fed intermittently by the drive roller 39 and the follower roller 40 toward a bending die 43 until it is pressed against and bent by a deflecting face 43a of the bending die 43 whereafter it is wrapped into coils around a metal core 45. The wire stock 42 is then cut to form a spring having a predetermined developing length l by a cutter 46 which is operated in a mechanically synchronized relationship to the rotation of the main shaft 31 when a pair of wire stock feeding rollers 41 consisting of the drive roller 39 and the follower roller 40 are stopped.
In producing a spring in such a manner, determination of a pitch of a spring S to be produced is made in a following manner. In particular, referring to (a) and (b) of FIG. 9, a pitch shaft 52 is slidably displaced in an axial direction thereof via a cam follower 49, a support shaft 50 and a pitch lever 51 by a cam 47 which is secured to and rotated by the aforementioned main shaft 31 until a predetermined portion of the wire stock 42 shaped into coils and wrapped around the metal core 45 (refer to FIG. 8) is pressed in the rightward direction as viewed in (a) of FIG. 9 and in a direction from the top to the bottom as viewed in (b) of FIG. 9 and by a pitch tool 53 securely mounted at an end of the pitch shaft 52.
Meanwhile, adjustment of the coil diameter and the profile of a spring to be produced is attained by adjustment of the position of the deflecting face 43a of the bending die 43 relative to the metal core 45 via a cam follower 56, a support shaft 57 and a lever 59 by a further cam 55 which is rotated by the aforementioned main shaft 31 as shown in FIG. 10. More particularly, if a circular cam of a predetermined radius is used which rotates around a shaft so that the position of the bending die 43 may not be changed by the cam 55, a spring to be produced will be an ordinary cylindrical spring of a predetermined coil diameter, but if such a cam is employed that the position of the die 43 is gradually moved away from the metal core 45 by the cam 55, a spring to be produced will present a conical configuration.
By the way, with the conventional spring producing apparatus 30 described above, in order to change the developing length of a spring S to be produced, it is necessary to change, for example, the length of the crank device 32 to change the wire stock feeding rate by the pair of wire stock feeding rollers 41; in order to change the pitch of the spring S, it is necessary to change the cam 47 to vary the moving amount of the pitch tool 53; and in order to change the coil diameter or the profile of a spring S, it is necessary to change the cam 55 to vary the position or the moving amount of the bending die 43. Accordingly, when a type of spring to be produced is to be changed, considerably high skill is required for such a changing operation, and much time is required for preparations. Accordingly, there is a drawback that the spring producing apparatus is not suited for experimental production of several types of coil springs.
In the drawings, reference symbol C denotes connection to a controller not shown.